shell: improved shell_prompt_change function

Shell will store only pointer to the prompt string instead of
copying it to the RAM buffer. It will save RAM memory and
it will simplify implementation of a  new feature: "select"
command. When a command will be selected than shell will
display command syntax as a prompt.

Removed obsolete ASSERT check in a static function.

Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>

include/shell/shell.h

@@ -401,6 +401,8 @@ enum shell_signal {
  * @brief Shell instance context.
  */
 struct shell_ctx {
+	const char *prompt; /*!< shell current prompt. */
+
 	enum shell_state state; /*!< Internal module state.*/
 	enum shell_receive_state receive_state;/*!< Escape sequence indicator.*/
 
@@ -447,7 +449,7 @@ enum shell_flag {
  * @brief Shell instance internals.
  */
 struct shell {
-	char *const prompt; /*!< shell prompt. */
+	const char *default_prompt; /*!< shell default prompt. */
 
 	const struct shell_transport *iface; /*!< Transport interface.*/
 	struct shell_ctx *ctx; /*!< Internal context.*/
@@ -475,7 +477,7 @@ extern void shell_print_stream(const void *user_ctx, const char *data,
  * @brief Macro for defining a shell instance.
  *
  * @param[in] _name		Instance name.
- * @param[in] _prompt		Shell prompt string.
+ * @param[in] _prompt		Shell default prompt string.
  * @param[in] _transport_iface	Pointer to the transport interface.
  * @param[in] _log_queue_size	Logger processing queue size.
  * @param[in] _log_timeout	Logger thread timeout in milliseconds on full
@@ -488,7 +490,6 @@ extern void shell_print_stream(const void *user_ctx, const char *data,
 		     _log_queue_size, _log_timeout, _shell_flag)	      \
 	static const struct shell _name;				      \
 	static struct shell_ctx UTIL_CAT(_name, _ctx);			      \
-	static char _name##prompt[CONFIG_SHELL_PROMPT_LENGTH + 1] = _prompt;  \
 	static u8_t _name##_out_buffer[CONFIG_SHELL_PRINTF_BUFF_SIZE];	      \
 	SHELL_LOG_BACKEND_DEFINE(_name, _name##_out_buffer,		      \
 				 CONFIG_SHELL_PRINTF_BUFF_SIZE,		      \
@@ -502,7 +503,7 @@ extern void shell_print_stream(const void *user_ctx, const char *data,
 	static K_THREAD_STACK_DEFINE(_name##_stack, CONFIG_SHELL_STACK_SIZE); \
 	static struct k_thread _name##_thread;				      \
 	static const struct shell _name = {				      \
-		.prompt = _name##prompt,				      \
+		.default_prompt = _prompt,				      \
 		.iface = _transport_iface,				      \
 		.ctx = &UTIL_CAT(_name, _ctx),				      \
 		.history = SHELL_HISTORY_PTR(_name),			      \
@@ -660,9 +661,9 @@ void shell_process(const struct shell *shell);
  * @param[in] prompt	New shell prompt.
  *
  * @return 0		Success.
- * @return -ENOMEM	New prompt is too long.
+ * @return -EINVAL	Pointer to new prompt is not correct.
  */
-int shell_prompt_change(const struct shell *shell, char *prompt);
+int shell_prompt_change(const struct shell *shell, const char *prompt);
 
 /**
  * @brief Prints the current command help.

samples/subsys/shell/shell_module/prj_minimal.conf

@@ -13,9 +13,7 @@ CONFIG_SHELL_STACK_SIZE=1024
 CONFIG_SHELL_CMD_BUFF_SIZE=128
 CONFIG_SHELL_WILDCARD=n
 CONFIG_SHELL_DYNAMIC_CMDS=n
-CONFIG_SHELL_PROMPT_LENGTH=10
 CONFIG_SHELL_VT100_COLORS=n
 CONFIG_SHELL_HELP_ON_WRONG_ARGUMENT_COUNT=n
 CONFIG_SHELL_STATS=n
 CONFIG_SHELL_CMDS=n
-

samples/subsys/shell/shell_module/prj_minimal_rtt.conf

@@ -13,7 +13,6 @@ CONFIG_SHELL_STACK_SIZE=1024
 CONFIG_SHELL_CMD_BUFF_SIZE=128
 CONFIG_SHELL_WILDCARD=n
 CONFIG_SHELL_DYNAMIC_CMDS=n
-CONFIG_SHELL_PROMPT_LENGTH=10
 CONFIG_SHELL_VT100_COLORS=n
 CONFIG_SHELL_HELP_ON_WRONG_ARGUMENT_COUNT=n
 CONFIG_SHELL_STATS=n

subsys/shell/Kconfig

@@ -37,12 +37,6 @@ config SHELL_BACKSPACE_MODE_DELETE
 	  Some terminals send code: 0x08 (backspace) other 0x7F (delete). When
 	  this option is set shell will expect 0x7F for backspace key.
 
-config SHELL_PROMPT_LENGTH
-	int "Maximum prompt length"
-	default 16
-	help
-	  Maximum length of prompt name in bytes.
-
 config SHELL_CMD_BUFF_SIZE
 	int "Shell command buffer size"
 	default 256

subsys/shell/shell.c

@@ -1069,8 +1069,6 @@ static void shell_log_process(const struct shell *shell)
 static int instance_init(const struct shell *shell, const void *p_config,
 			 bool use_colors)
 {
-	__ASSERT_NO_MSG(shell);
-	__ASSERT_NO_MSG(shell->ctx && shell->iface && shell->prompt);
 	__ASSERT_NO_MSG((shell->shell_flag == SHELL_FLAG_CRLF_DEFAULT) ||
 			(shell->shell_flag == SHELL_FLAG_OLF_CRLF));
 
@@ -1082,6 +1080,7 @@ static int instance_init(const struct shell *shell, const void *p_config,
 	}
 
 	memset(shell->ctx, 0, sizeof(*shell->ctx));
+	shell->ctx->prompt = shell->default_prompt;
 
 	history_init(shell);
 
@@ -1098,7 +1097,7 @@ static int instance_init(const struct shell *shell, const void *p_config,
 	shell->ctx->state = SHELL_STATE_INITIALIZED;
 	shell->ctx->vt100_ctx.cons.terminal_wid = SHELL_DEFAULT_TERMINAL_WIDTH;
 	shell->ctx->vt100_ctx.cons.terminal_hei = SHELL_DEFAULT_TERMINAL_HEIGHT;
-	shell->ctx->vt100_ctx.cons.name_len = shell_strlen(shell->prompt);
+	shell->ctx->vt100_ctx.cons.name_len = shell_strlen(shell->ctx->prompt);
 	flag_use_colors_set(shell, IS_ENABLED(CONFIG_SHELL_VT100_COLORS));
 
 	return 0;
@@ -1107,7 +1106,7 @@ static int instance_init(const struct shell *shell, const void *p_config,
 static int instance_uninit(const struct shell *shell)
 {
 	__ASSERT_NO_MSG(shell);
-	__ASSERT_NO_MSG(shell->ctx && shell->iface && shell->prompt);
+	__ASSERT_NO_MSG(shell->ctx && shell->iface);
 
 	int err;
 
@@ -1219,7 +1218,7 @@ int shell_init(const struct shell *shell, const void *transport_config,
 	       bool use_colors, bool log_backend, u32_t init_log_level)
 {
 	__ASSERT_NO_MSG(shell);
-	__ASSERT_NO_MSG(shell->ctx && shell->iface && shell->prompt);
+	__ASSERT_NO_MSG(shell->ctx && shell->iface && shell->default_prompt);
 
 	int err = instance_init(shell, transport_config, use_colors);
 
@@ -1259,7 +1258,7 @@ int shell_uninit(const struct shell *shell)
 int shell_start(const struct shell *shell)
 {
 	__ASSERT_NO_MSG(shell);
-	__ASSERT_NO_MSG(shell->ctx && shell->iface && shell->prompt);
+	__ASSERT_NO_MSG(shell->ctx && shell->iface && shell->default_prompt);
 
 	if (shell->ctx->state != SHELL_STATE_INITIALIZED) {
 		return -ENOTSUP;
@@ -1367,20 +1366,16 @@ void shell_fprintf(const struct shell *shell, enum shell_vt100_color color,
 	}
 }
 
-int shell_prompt_change(const struct shell *shell, char *prompt)
+int shell_prompt_change(const struct shell *shell, const char *prompt)
 {
-	u16_t len;
-
 	__ASSERT_NO_MSG(shell);
-	__ASSERT_NO_MSG(prompt);
 
-	len = shell_strlen(prompt);
+	if (prompt == NULL) {
-
+		return -EINVAL;
-	if (len <= CONFIG_SHELL_PROMPT_LENGTH) {
-		memcpy(shell->prompt, prompt, len + 1); /* +1 for '\0' */
-		return 0;
 	}
-	return -ENOMEM;
+	shell->ctx->prompt = prompt;
+
+	return 0;
 }
 
 void shell_help(const struct shell *shell)

subsys/shell/shell_ops.c

@@ -30,14 +30,14 @@ void shell_op_cursor_horiz_move(const struct shell *shell, s32_t delta)
  */
 static inline bool full_line_cmd(const struct shell *shell)
 {
-	return ((shell->ctx->cmd_buff_len + shell_strlen(shell->prompt))
+	return ((shell->ctx->cmd_buff_len + shell_strlen(shell->ctx->prompt))
 			% shell->ctx->vt100_ctx.cons.terminal_wid == 0);
 }
 
 /* Function returns true if cursor is at beginning of an empty line. */
 bool shell_cursor_in_empty_line(const struct shell *shell)
 {
-	return ((shell->ctx->cmd_buff_pos + shell_strlen(shell->prompt))
+	return ((shell->ctx->cmd_buff_pos + shell_strlen(shell->ctx->prompt))
 			% shell->ctx->vt100_ctx.cons.terminal_wid == 0);
 }
 
@@ -346,10 +346,10 @@ static void print_prompt(const struct shell *shell)
 
 		shell_vt100_colors_store(shell, &col);
 		shell_vt100_color_set(shell, SHELL_INFO);
-		shell_raw_fprintf(shell->fprintf_ctx, "%s", shell->prompt);
+		shell_raw_fprintf(shell->fprintf_ctx, "%s", shell->ctx->prompt);
 		shell_vt100_colors_restore(shell, &col);
 	} else {
-		shell_raw_fprintf(shell->fprintf_ctx, "%s", shell->prompt);
+		shell_raw_fprintf(shell->fprintf_ctx, "%s", shell->ctx->prompt);
 	}
 }